This invention relates to an instrument for applying surgical staples to body tissue. More particularly, the invention relates to a surgical stapler which has been adapted to more easily grip tissue between the tissue contacting surfaces of the instrument.
There is an increasing use of surgical stapling instruments to suture body tissue such as intestine, lung, stomach, and esophagus. Stapling tissue in most instances produces less scar tissue formation, requires less time and simplifies previously difficult surgical procedures when compared with traditional suturing methods. Surgical staplers of the type used in these procedures function generally by clamping the tissue between two opposed jaw components of the instrument. After the tissue is squeezed to a desired thickness, staples are fired through the tissue causing intimate contact of the tissue layers. Proper healing of tissue requires such contact, along with adequate blood supply.
Typically, the opposed jaw components of surgical staplers used to fasten layers of body tissue are a cartridge or staple holding jaw and an anvil or staple forming jaw. Such stapling devices are typically designed to apply multiple parallel rows of staples. Some staplers provide pairs of staple rows with a movable knife between the row pairs. The knife is important when tissue is required to be separated.
Mechanisms for clamping the tissue by closing the jaw components and forming the staple are typically included in such surgical staplers. U.S. Pat. No. 4,527,724, shows a linear stapler having an anvil jaw and a staple holding jaw. This type of stapler forms at least two parallel rows of staples but has no knife. The tissue clamping and staple forming functions are performed remotely from the tissue contact end of the device. U.S. Pat. Nos. 4,429,695, 4,633,861, and 4,633,874 show other linear stapler variations, each having an anvil jaw and staple holding jaw component in addition to a movable tissue cutting knife.
In order to produce the most desirable result in a surgical stapling procedure, the staples must be placed in the exact location desired by the surgeon and the resulting cut edge of tissue retain adequate blood supply for healing after stapling. The surgeon selects the precise location for the staple line, then places the opposed jaws over the tissue at that location and clamps the jaws together prior to firing the staples and cutting the tissue. Body tissue is usually kept moist on the surface during the surgical procedure and tends to slip out of the clamped jaws. Most surgical staplers utilize a pin to help align the jaw components for better staple formation, but the pin also tends to hold the tissue in place during the stapling procedure. The pin, however, holds tissue at one location only, requiring the jaw component surfaces to hold the remaining line of tissue layers in proper position. U.S. Pat. No. 5,014,899 shows a spring loaded button which is intended to hold tissue at one location between the jaws of a surgical stapler. Unfortunately, the net effect of these mechanisms to hold the tissue are that the tissue layers to be stapled can slip between the jaw components resulting in an irregular staple line and cut edge. This result can require the stapling procedure to be repeated which may not be possible because of lack of usable remaining tissue.
Not only is it desirable to hold the clamped tissue layers in the chosen position, but also to allow adequate blood supply at the cut edge. If inadequate blood supply occurs, healing either does not take place or is very slow. Selection of the final jaw closing gap value is a major factor in tissue healing after stapling.
One method of increasing the blood supply at the staple line is to compress the tissue to such an extent that crushing or bruising of body tissue occurs. The jaw closing gap value can be selected to cause tissue crushing which will occur over the entire tissue contact surface of the jaw components. This choice can also result in a staple height which is too small and will cause necrosis of tissue around the staples after the jaws are opened because the blood supply is restricted by the small staple height.
Accordingly, in view of the tissue clamping deficiencies in current surgical linear staplers, what is needed is a better way to hold clamped tissue in its chosen position until completion of the stapling and cutting procedure. In addition to the better way of holding clamped tissue, a better tissue healing condition is desirable by restricting the area to be crushed, thereby increasing the blood supply to the desired level.